problem.purs

overlap :: Int -> Int -> Int -> Int -> Boolean
overlap a b c d = (c < b && d > a) || (d > a && c < b)

instance tupleInt :: Semigroup IntTuple where
  append (IntTuple (Tuple a b)) (IntTuple (Tuple c d)) =
    if (overlap a b c d)
      then IntTuple $ Tuple (min a c) (max b d)
      else IntTuple $ Tuple a b

sanitizeTupleList' :: List IntTuple -> List IntTuple
sanitizeTupleList' Nil = Nil
sanitizeTupleList' (x:xs) = nub (getAggregateValue x xs : sanitizeTupleList' xs)
  where
    getAggregateValue :: IntTuple -> List IntTuple -> IntTuple
    getAggregateValue tuple = foldl (\t1 -> \t2 -> append t1 t2) tuple

sanitizeTupleList :: List IntTuple -> SanitizedList
sanitizeTupleList = removeOverlapping <<< nub <<< sanitizeTupleList' where
  removeOverlapping :: List IntTuple -> SanitizedList
  removeOverlapping Nil = SanitizedList Nil
  removeOverlapping l = SanitizedList $ filter (not $ isContained l) l
  isContained :: List IntTuple -> IntTuple -> Boolean
  isContained l' (IntTuple (Tuple a b)) = isJust $ find (\(IntTuple (Tuple c d)) -> ((a > c && b <= d) || (a >= c && b < d))) l'